Tube stretching apparatus



May ll, 1965 E. H. ARNAUDIN, JR

TUBE STRETGHING APPARATUS Filed May e, 196s R In. N m m m u f WM J m W Hn m w D E z Q o mwzzou 55 MQ w .Sl 595m 5G; o?

Nw T km mm v United States Patent Oice 3,182,355 Patented May 11, 19653,182,355 TUBE STRETCHING APPARATUS Edwin H. Arnaudin, Jr., Marion,Ind., assigner, by mesne assignments, to Anaconda Wire and CableCompany, a

corporation of Delaware Filed May 6, 1963, Ser. No. 278,085 6 Claims.(Cl. 18-19) My invention relates to apparatus for stretching lengths ofshrinkable tubing and particularly to such apparatus for stretchingtubing while heating the same and for cooling the said tubing in astretched condition.

To manufacture shrinkable tubing, lengths of the tubing are stretchedradially while at a temperature higher than that at which the tubingwill be used but below its softening point. The tubing is thereaftercooled while still in the stretched condition. It is Ia property oftubing of the type for which the apparatus of my invention is intendedthat it will retain its stretched dimensions for long storage periods atroom temperature but will return to its original dimensions if it isagain heated to some critical temperature that is below its softeningpoint. If, upon reheating, the shrinkable tubing is mechanicallyrestrained from fully shrinking to its original dimensions, it willremain in a condition of elastic stretching and exert a pressure uponthe restraining means. Where the restraining means is an electricalconnection or joint it is desirable to have the tubing shrink radiallybut not lengthwise since there would be nothing to restrain thelengthwise shrinkage and the joint would be uncovered by any shorteningof the tubing due to shrinkage. To prevent lengthwise shrinkage of thestretched tubing it is essential that the initial stretching shall beradial only, with no increase taking place in the original length oftubing.

For the above stated purpose I have invented a tube stretching apparatuscomprising a length of pipe with a wall sufiiciently thick to withstandatmospheric pressure and a plurality of perforations positioned in atleast one straight line. Preferably my pipe has two lines ofperforations spaced 180 apart which have surprisingly been found capableof expanding the tubing to till the entire pipe. My apparatus alsocomprises means forming at least one chamber lengthwise of the pipeenclosing the line of perforations and hermetically sealed to the pipewith the pipe forming one of the walls of the chamber. There are meansevacuating the chamber thereby stretching the tub-ing and means sealinga flexible tubing that is contained within the pipe to the pipe endswhile still permitting fluid to enter the tubing. My apparatus alsocomprises means for heating and preferably also for cooling the pipe,such as a container enclosing the pipe through which a temperaturecontrolling fluid can be circulated.

A more thorough understanding of my apparatus can be gained by referenceto the appended drawing.

In the drawing:

FIGURE l is a lengthwise section through my apparatus. Y

FIGURE 2 is a section through the lines 2 2 of FIG- URE 1.

In the embodiment of my apparatus shown in the drawing a pipe 11 havinga length about equal to lengths of tubing 12 to be stretched has twolines 13, 14 of perforations 16 through its walls. YA lengthwise chamber17 lencloses the line of holes 13 and a similar chamber 18 encloses theline of holes 14. The chambers 1-7, 18 which are conveniently made fromhalf-cylinders 19, 2liy are completed by sections 21, 22 of the pipe 1-1to which the halfcylinders are sealed by lengthwise welds 23. Theends ofthe` chambers 17, 18 are closed by walls 24 sealed by means of welds 26to the half-cylinders 19, 20 and by welds 27 to the pipe v11. A Vacuumnipple 28 communicates with the chamber 17 and is hermetically sealed tothe half-cylinder 19 by means of welds 29, and a similar vacuum nipple31 communicates with the chamber 18 and -ishermetically sealed to thehalf-cylinder 20 by means of welds 32. A ground sleeve 33 and a iitting34 are hermetically sealed to the respective left and right ends of thepipe 11 by means of respective welds 36, 37. The sleeve 33 and fitting34 are accurately ground at the cylindrical surfaces 3S, 39 and endsurfaces 41, 42 to accept adaptors 43, 44 which are ground to have avacuum tight it over the sleeve 33 and -itting 34. The adaptors 43, 44have tapered bores 46, 47 which match tapered plugs 48, 49. The length12 of tubing to be stretch is sealed within the pipe 11 by wedging oneend portion 51 between the plug 4S and the bore 46 and another end 52.between the plug 49 and bore 47. Both, or at least one of the plugs 4S,49 has a central bore S3 which permits free air or air, or other uid,under controlled pressure to enter the length of tubing 12. When tluidunder controlled pressure is to be introduced into the tubing 12, aflexible hose of known type can be tted over the plug 48 while the plug49 will be free from any bore 53. Alternatively the plug 48 may bethreaded in a known manner to accept a threaded hose coupling. Acylindrical container or jacket 54 encloses almost the entire length ofthe pipe 11 and the half-cylinders 19, 20. The jacket S4 is closedaround the pipe 11 by end sections 56, 57. Nipples 58, S9 connect thejacket to a cold water supply not shown by means of valves arranged in aknown manner and also not shown. Additional nipples 61, 62 connect thecontainer to a steam supply and a condensate drain in a known mannerwith appropriate valves not shown.

In order to permit dilferential expansion of the tube 11 relative to thejacket 54 the end section 56 which has a slide tit on the sleeve y33 ismade wide enough to contain a recess 63 for steam packing 64. Thepacking 64 can be compressed by an` insert `61S upon tightening threadedbolts 67.

Operation To expand a length 12 of tubing by means of rny apparatus itis itted within the pipe 11 and secured by the plugs 48, 49 in suchmanner that there is no air leakage between the outside of the tubingand the inside of the pipe. Steam is then introduced through the nipple61 into the jacket 54 until the tubing has reached a temperature belowits softening point at which it can be stretched without returning toits original shape when cold. The air is then evacuated through thenozzles 28, 31 by known means to exhaust the chambers 17, 18. The air isthus drawn from the pipe 11 externally of the tubing 12 through theholes 16. Surprisingly, I have discovered that although there are only 2rows of such holes the tubing 12 will be thoroughly stretched in aradial direction and that it is not necessary to make the pipe 1-1 of aporous material or to have perforations distributed over its entirecircumference. The advantage of this discovery is that the heating andcooling Ifluids can thus be applied directly to the pipe 11 at the majorarea of its surface that is not covered by the half-cylinders 19, 2t?.If a porous pipe were used it would, of course, be necessary to surroundit entirely with a vacuum chamber and heattransfer directly to and fromthe pipe, and thus to and from the tubing 12 would be impossible.

After the tube has expanded, the steam is turned off while stillmaintaining vacuum and cold water is permitted to pass through thecontainer 54 until the tubing 12 has cooled, preferably, at least toroom temperature. IDuring the cooling cycle the length of tubing 12 isWhen the tubing has cooled, the plugs 53, `d are retched tubing iswithdrawn from the I have invented a new and useful apparatus for whichI desire an award of Letters Patent.

l claim:

l. Apparatus for stretching tubing comprising:

(1A) a length of pipe having a wall sufliciently thick to withstandatmospheric pressure,

(B) a plurality of perforations through said pipe,

(a) said perforations being positioned in a straight line on the surfaceof said pipe,

(C) means forming a chamber lengthwise of said pipe (a.) having saidpipe as one of the walls thereof, (b) said chamber enclosing said lineof perforations and (c) said 'chamber being hermetically sealed to saidpipe so as to leave a major area of said pipe uninclosed thereby,

(D) means evecuating said chamber thereby stretching said tubing, i (E)Vmeans sealing a length of flexible tubing contained within said pipe tothe ends thereof =(a) while permitting fluid to enter said tubing, and

(KF) means heating said pipe.

2. Apparatus for stretching tubing comprising:

(-A) a length of pipe having `a wall suthciently thick to withstandatmospheric pressure,

(B) a pluralityof perforations through said pipe,

(a) said perforations being positioned in a straight line c-n thesurface of said pipe,

y(C) means forming a chamber lengthwise of said pipe (a) having saidpipe as one of the walls thereof, (b) said chamber enclosing said ylineof perforations and (c) said chamber being hermetically sealed to saidkVpipe so as to leave a major area of said pipe` uninclosed thereby, Y(D) means evacuating said chamber thereby stretching said tubing, v (E)means sealing a length of flexible tubing contained within said pipe tothe ends thereof (a) while permitting fluid to enter said tubing, and(F) means alternately heating and cooling said pipe. 3. Apparatus forstretching tubing comprising: *Y (A) a length of pipe having a wallsufficiently thick to withstand atmospheric pressure, (B) a plurality ofperforations through said pipe,

(a) said perforations'being,positioned in a straight line on the surfaceof said pipe, (C) means forming a chamber lengthwise of said pipe (a)having said pipe Vas one ofthe Walls thereof, t(b) said chamberenclosing said line of holes, and (c) said chamber being hermeticallysealed to said pipe so as to leave a major area of said pipe uninclosedthereby, (D) means evacuating said chamber thereby stretching saidtubing, i (IE) ymeans sealing a length of llexible tubing containedWithin said pipe to the ends thereof, Y v (a) while permitting luid toenter said tubing, (E) a container enclosing said pipe, and

`(G) `means for circulating temperature controlling fluid through saidcontainer.

' 4.V Apparatus for stretching tubing comprising:

(A) a length'of pipe having a wall sufficiently thick to withstandatmospheric pressure, (B) la plurality of perforationsfthroughsaidvpipe, i

(a) said perforations -beingpositioned in ,two Y straight lines, 180degrees apart, on the surface of said pipe, i l

(C) means forming two chambers lengthwise of said pipe,

(a) each of said chambers having said pipe as one of the walls thereof,(b) each of said chambers enclosing onefof said lines of perforations,`and (c) said chambers being hermetically sealed to said pipe so as toleave a major area of said pipe uninclosed thereby, (D) means evacuatingsaid chambers thereby stretching said tubing, (E) Vmeans for sealingsaid tubing contained within said pipe to the endsthereof, (a) whilepermitting fluid to enter said tubing, and (F) means heating said pipe.5. Apparatus for stretching tubing comprising: (A) a length of pipehaving a wall sufficiently thick t0 withstand atmospheric pressure, (B)a plurality of perforations through said pipe,

(a) said perforations `being positioned in two straight lines, 180degrees apart, (C) means vforming two chambers lengthwise of said plpe:

(a) each of `said chambers'having said pipe as one of the walls thereof,

(b) each of said chambers enclosing one of said lines of Aperforations,and:

(c) said chambers being hermetically sealed to said pipe so as to leavea major area of said `pipe uninclosed thereby,

(D) `means for evacuating said chambers thereby stretching said tubing,(E) means for sealing saidV tubing contained within said pipe to theends thereof, i '(Lz) while permitting fluid to enter said tubing, and

(F) means for heating and cooling said pipe.V 6. YApparatus forstretching tubing comprising: (A) a length of pipe having a wallsuiciently thick to withstand atmospheric pressure, f (B) a plurality ofperforations through said pipe,

(a) said perforations being positioned in two straight lines,liSOrdegrees apart,

(C) means forming two chambers lengthwiseV of said (a) each of saidchambers havingsaid pipe as one Vof the walls thereof, V(b) each kofvsaid chambers-enclosing one of said Vlines of perforations, and l (c)said chambers being hermetically sealed to said ypipe soas to leave amajor area of said pipe uninclosedthereby, Y (D) means for evacuatingsaid chambers thereby ,stretching said tubing, Y (E) means for sealingsaid tubing contained within said pipe to the ends thereof, i

,'(cz)--while permitting iluid to enter said tubing, (F) a containerenclosing said pipe, and (G) means'for ycirculatingtemperature,controlling-iluid through said container.V 1

- References Cited by Vthe Examiner UNITED STATES PATENTS

1. APPARATUS FOR STRETCHING TUBING COMPRISING: (A) A LENGHT OF PIPEHAVING A WALL SUFFICIENTLY THICK TO WITHSTAND ATMOSPHERIC PRESSURE, (B)A PLURALITY OF PERFORATIONS THROUGH SAID PIPE, (A) A SAID PERFORATIONSBEING POSITIONED IN A STRAIGHT LINE ON THE SURFACE OF SAID PIPE, (C)MEANS FORMING A CHAMBER LENGTHWISE OF SAID PIPE (A) HAVING SAID PIPE ASONE OF THE WALLS THEREOF, (B) SAID CHAMBER ENCLOSING SAID LINE OFPERFORATIONS AND (C) SAID CHAMBER BEING HERMETICALLY SEALED TO SAID PIPESO AS TO LEAVE A MAJOR AREA OF SAID PIPE UNINCLOSED THEREBY,